OpenMsgStore failed

Hi,

after some trouble with BES installation with ZCB, now BES is running. Yes running, but nothing more.
I can see "some" users, not all and the main problem is the error in AgentLog: OpenMsgStore failed. I can see, that the ETP message arrives at users mailbox, but BES don't pick the message up. I have set the BESAdmin to GlobalAdmin and assigned to "Allow sending email from any address". But it doesn't work.
I know from BES for Exchange installations, that a couple of permissions have to be set on exchange if the BES works. But should BES Admin under Zimbra really works with the less permissions?